In coupling or uncoupling operations with a tractor cab and dual trailers, accurate longitudinal alignment of the first and second trailers and the fifth wheel dolly positioned between the trailers is essential to prevent damage to certain vulnerable components situated near the coupling area. Needless to say, any required repair following such damage interrupts the normal routine of the maintenance mechanics, and causes inevitable delay to the shipment. It is also apparent that any reduction in the necessary time for coupling the trailer will maximize the road time for the tractor-trailer vehicle. This is a clear advantage to the owners, whose mechanics might otherwise be called off major repair work.
In dimly lit truck yards, the usual practice among truck drivers of using the brake lights of the semitrailer and/or the flashing turn signals of the semitrailer is totally inadequate to always assure rapid and effective coupling to a fifth wheel dolly and second trailer. The present invention enables quick, safe and easy coupling operations in inadequately lit truck yards.